Fuse



May 24, 1932. F, c. LA MAR 1,860,313

- FUSE Filed. Feb, 19, 1930 Z, @Q ATTORNEY Patented May 24, 1932 UNITED STATES PATENT OFFICE FRANK C. LA. OF NEW YORK, N. Y., ASSIGNOR T0 GREAT WESTERN FUSE COM- PANY, OF NEW YORK, N. Y., .A CORPORATION 0F DELAWARE FUSE Application iilei February 19, 1930. Serial No. 429,473.

This invention relates to electrical devices, especially to electrical devices for interrupting, an electrical circuit upon an abnormal flow of current therein and more particularly to such a device including an easily fusible link commonly known as a fuse.

Heretofore fuses of the renewable cartridge type have been made in many forms. These forms have apparently been devised in an attempt to produce a renewable fuse ofV the cartridge type which consisted of. a minimum of parts, inexpensive to assemble, and Which-was so constructed that to remove the fusible element from the cartridge in order to replace it with a new fusible element would .require the fewest manipulations and the fewest and most commonly used tools.

A principal object of applicants invention is the provision -of a renewable fuse of the ca rtridge type which is so constructed that a mmimum of parts must be disassembled in order to replace the fusible element and which preferably does not require the use of any tools whatsoever.

A further object of the invention is the provision of a device of the type described which includes knife blades held in alignment by an insulating bridge.

A further object of the invention is the provisionk of a device of the type described,

including an insulating bridge for maintaining knife blades .in alignment and means for securing the ends of the bridge to the knife blades, of such a form that the bridge may be removed and replaced by a newbridge by theluse of the fewest possible commonly used too s.

Other objects and advantages will appear as the description of theparticular physical,

embodiment selected to illustrate -the invention progresses and the novel features of the invention will be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiment selected to illustrate the invention reference will be had to the accompanying drawings and the several views thereon in which like characters of reference designate corresponding parts throughout, and lin which:

device as shown by Fig. 1; Fig. 5 is a top plan View of a unitary knife blade assembly as used in the device.

In general the device comprises an insulating shell or tube 1 having at each end identically formed ferrules as 2, identically formed end caps as 3, identically formed closure washers 'as 4, and avknife blade assembly designated as a Whole by A, including oppositely disposed identically formed separated knife blades 5 protruding from each end of the shell 1.

Each of the knife blades has a shoulder also preferred to have a slot in the disc and l of such size that it will pass over the tang 5 of the knife blade but will abut the shoulders as 52 of the knife blade.

Abuttin'g the shoulder 61on the blade 5 is the closure washer 4 which .is formed on" its inner side with projections at intervals, as 4'.. c c

'The cap 3 is formed with an internal thread 3 and a' flange 32.. The internal thread 3 contacts4 with an external thread 2 upon the ferrule 2 and the flange 32 is of such size that the blade 5 may pass therethrough but the ange will bear against the closure washer 4.

The dimensions of the parts are such that the shoulder 6 may pass through the shell 1 and ferrules 2 from end to end; the washer 4 has its projections 4 bearing against the end Wall of the ferrule 2 providing va slight gas space therebetween; thel cap 3l when screwed into place, as shown in Fig. 2, holds the closure washer 4 firmly against the shoulder 6 and the projections '45"'thereof`firmly against the end of the ferrule 2 but the inner end of the cap comes just short of meeting the shoulder 22 of the-ferrule.

In order to maintain the knife blades 5 in spaced relation longitudinally and in alignment, the insulating bridge 7 is used. This bridgev may be made of many different materials but it is preferred to usehorn fibre.-

The cross-section of the bridge may be of various forms but it has been found that an arcuate form is preferable. This form ofcross-section 'is shown in Fig. 3. It provides the maximum of material adjacent the shell and the maximum separation from the fusible l ets have a-flat link`8. In order to attach the bridge to the tangs 5 of the blades with a minimum of parts and a maximum of efficiency in maintaining spacing and alignment, applicant has provided the end sockets 9. These end sockportion 9 bearing against the flat 'side' of the tank and are preferably riveted thereto by rivets as 10. Each socket has bent up edges 92 which conform to the outer portion of the arcuate bridge member 7. The arcuate bridge memberl 7 is positioned by being slipped longitudinally until it abuts against the shoulders as 6. The

knife blades are thereby spaced and aligned.4

` l In order to hold the bridge in position and to also hold the renewable fuse link 8 in position, a vfiat headed screw 11 is passed through 'a counter sunk orifice in theA bridge and threaded into an orifice in thetang 5 and extending up beyond the tank 5 provides a threaded rod like member about ers 13 firmly againstthe ends of the fusible link 8 to hold them 1n place.

- l `If a'fusible link as 8'fuses -then in,A order to replace it with' a new fusible linkitgis,

necessary to remove only one of the end caps When an end cap as 3 is removed, the unitary fuse link device A may be then withdrawn from the shell'l. After being withdrawn from the shell l'it is merely necessary -to loosen the two wing nuts '12, removethe remnants of the old fuse link, substitute a new fuse link 8,`then tighten the wing nuts,

they maybe ventirely withdrawn, a new ininto the sockets 9 4 which the fl ends of the fusible link 8 are passed and which f bear wing nuts 124 for clamping the washvwith the other end of the bridge sulating bridge 7 put into place, and the screws replaced. l

When a fusible link is fused inservice the gases formed within the shell pass around the end of the ferrules 2 between the washer 4 and the ferrule into the threads 3 and 2, around the threads, flnall space 14 between the end ofy the cap 3 and the shoulder 22 ofthe ferrule.

From' the above description it will be seen that a new fusible link may be inserted in the device without the use of any tools whatsoever, although of course, applicant does not mean to exclude the use of ordinary nuts in place of the wing nuts 12, in which case, a wrench or pliers of some sort would be probably required. The only other part of the issuing at the interior ofthe fuse which may possibly need renewing 4being the insulating bridge 7, provision has been made'so that 1t may be readily renewed by the use of no tools other'than perhaps a screw driver, and a pair of pliers if an ordinary nut is used in place of the wing construction thereof, nevertheless, I desire to have it understood that the form selected is ymerely illustrative but does not exhaustv the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a renewable cartridge fuse, in combination: a hollow insulating body; a metallic ferrule attached onone end of the bodyv and provided with an external thread; a anged cap provided with an internal thread or cooperation with the external thread of the ferrule; a slotted washer formedwith projectionsresting on the end' of the ferrule clamped between the flange of the cap and the ferrule; a knife blade protruding through the ,slot in the washer, formed with a shoulder against which thewash'er bears and a threaded orifice for the reception of a screw threadedmember; a' socket attached to the knife blade; anelongated insulating bridge member having an end inserted in the socket; a headed screw threadedgmember passing through the bridge member, the socket, screw threaded into the knife blade and proJecting therethrough, a nut for cooperation with the projecting portion of the screw threaded member for attaching one end o f a fuse link to the knife blade and means cooperating member for forming another knife. blade spaced from the rst mentioned knife blade closing the other end of the hollow member and providing for the attachment of the other end of the fusible link.

2. In a knife blade assemblyfor a renewable cartridge fuse, in combination: two oppositely disposed separated knife blades; socket members; one attached to each knife blade; an insulating bridge having an end inserted in each socket; two headed screw threaded members; one passing through each end of the bridge and a socket threaded into a knife blade and projecting therebeyond; nuts, one on each screw threaded member for clamping an end of a fusible link to a knife blade.

3. In a knife blade assembly for a renew-v knife blade and formed with inward projecfor each tions; internally threaded flanged caps one cooperating with leach washer; externally threaded ferrules, one cooperating with each -capand a hollow enclosing body joining the ferrules.

4. IAs a means for spacing the knife blades of a renewable cartridge fuse, the combination withtwo spaced oppositely disposed threaded orificed knife blades of socket members one attached to each blade, an insulating bridge piece having opposite ends engaging the socket members and headed screw threaded members, one passing through each end of the bridge piece, through a socket screw threaded into a knife blade orifice and projecting therefrom and having a nut thereon for securing a fusible link to the knife blade. y

5. As a unitary assembly for the knife blades of a renewable fuse, the combination of: two separated knife blades; an insulating bridge member extending between and overlapping the end of each knifeblade; a socket resting against a flat face ofthe knife blade and upturned edges partially embracing the end of the bridge member; means fastenin the sockets to the blades and headed screwe members, onevpassing through each end of the bridge, through each socket andthreaded into "a blade and. extending therebeyond and provided with a nut to fasten one end of a link l to the blade. FRANK C. LA MAR.

knife blade formed with a lat face 

